The present invention relates to apparatus for preparing an edible product including a cylindrical core and an outer, cylindrical shell of coagulated egg-white mass. The apparatus comprises a plurality of vertically oriented cylindrical moulds which are open at their top and closed at their bottom, means for cyclically moving the moulds through a plurality of successive stations including a station for inserting a core member into each mould, a station for later withdrawing the core member, one or more stations for supplying liquid egg-white mass to the annular space defined between the inner wall of the mould and the core member, and for supplying a product core forming material to the space formed by the core member, a station for withdrawing finished products from the moulds, and means for heating and subsequently cooling the moulds during their travel through the stations.
The core of the finished products will normally consist of coagulated egg yolk, but may also consists of other edible materials such as minced meat, vegetables etc. or contain one or more such materials as additives to the yolk mass. Colouring agents, flavouring additives or preservatives may also be included in the egg-white and/or the product core. The cross-section of the product may be arbitrary, but its contour will in most cases be circular or smoothly curved, such as oval.
An apparatus of the kind referred to is disclosed in US Pat. specification No. 3,823,659. In the known apparatus each mould is formed as a relatively thin, longitudinally slit shell made of a curved metal sheet which, due to its resiliency, is held in tight engagement with a tubular member extending through a heating vessel in the apparatus. Each mould is withdrawn from the apparatus together with the finished product, and the mould may then expand radially whereby the product is released in such a way that the risk of adhesion between the mould surface and the coagulated shell of egg-white is rather small. Since the period necessary for coagulating the product can hardly be reduced much below about 20 minutes even when the liquid egg-white mass is preheated, an acceptable production rate of the apparatus can only be obtained by the provision of a considerable number of moulds, and the apparatus must include means for withdrawing the moulds and re-inserting them in two different stations, means for transferring empty moulds from one station to the other and means for cleaning the moulds outside of the apparatus before they are re-inserted. All this makes the apparatus rather complicated and expensive. It may also be difficult, in particular after prolonged use of the resilient moulds, to ensure a tight fit between the entire outer surface of the mould shells and the inner surface of the tubular members, which receive the moulds, and this may result in a reduced efficiency of the heat transmission to the product components within the moulds and hence in a reduced production rate.